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Thursday, August 31, 2017

Here is yet another study (Ellekjear 2017) showing that labor is often managed differently in "obese" women, with a lower surgical threshold being the most marked finding. The authors concluded:

Caesarean deliveries are undertaken earlier in obese women compared to normal weight women following the onset of active labour, shortening the total duration of active labour.

Research generally shows women of size probably need more time in labor in general, especially in the early stages, but once their labors get going, they usually go well. However, many care providers opt to terminate labor earlier and move quickly to a cesarean. They are understandably concerned about the risks of doing an emergent cesarean on a larger body, but they are usually giving up far too soon and causing an epidemic of "failure to wait" cesareans in women of size. .

There was an infamous Vaginal Birth After Cesarean (VBAC) and obesity study in 2001 that demonstrated this quite strongly. 30 women over 300 lbs. were "allowed" to labor for a VBAC, but only 13% of those who tried for a VBAC ended up with one. As a result, this was widely publicized as a reason not to "let" high-BMI women try for a VBAC and cited by doctors as a reason to deny fat women the opportunity to VBAC.

However, what the full text of the study actually reveals is that the majority of these women were induced, which is known to increase the chances of cesarean and lower the chances of VBAC. Interestingly, the only women who got a VBAC in this study were the ones who were not induced.Most tellingly, those who had cesareans had their labors stopped at an average of 4.5 cm of dilation. 4.5 cm barely qualifies for the old definition of active labor, and certainly doesn't fit with the new recommended definition of active labor (6 cm)! In other words, these high BMI women were not given an adequate chance to labor.

High induction rates and a lack of patience in labor are the main factors that drive the high cesarean rate in obese women.

Studies have shown that about half of high BMI women in general are induced, typically increasing cesarean rates. However, when allowed to go into spontaneous labor, cesarean rates are more equalized among BMI groups.

One earlier study found that high BMI women tended to take longer to progress in labor, especially between 4 and 7 cm of dilation. They urged far more patience in the labors of heavier patients.

Similarly, a 2016 study found that 57% of labors in high BMI first-time mothers were stopped before 6 cm of dilation; those mothers ended with cesareans. Failure to Wait is a major problem when doctors attend women of size.

More spontaneous labor and more time during labor would probably have yielded far better VBAC rates in that 2001 VBAC study. It should be pointed out that a look at some later studies showed VBAC rates around 50-70% in obese women, which could almost certainly be increased even more since they also reflect very high induction rates and the old active labor definition. Indeed, research from England shows that the majority of even very high BMI women can have a vaginal birth with different management.

The bottom line is that multiple studies have found that the labors of high BMI women are managed differently than the labors of average-sized women.In particular, too many inductions are being done, the surgical threshold is very low, and more patience is needed during labor. This represents an area that is ripe for change and offers hope for lowering the far-too-high cesarean rate in obese women.

As the authors of a Canadian study concluded about the management of high BMI women:

Because of the potential morbidities associated with Caesarean section, we must modify our management approaches to allow equal opportunity for a vaginal birth for all women.

Sunday, August 20, 2017

EXTRA, EXTRA! Researchers messed up the conclusion of earlier cesarean incision study! Transverse (side-to-side) incisions really are better after all for high BMI women!Vindication!

Background

For many years OBs were taught that a vertical incision was needed for very "obese" women because the area under a belly flap ("panniculus", sometimes referred to as a "pannus") was hot and moist and therefore prone to infection ─ in other words, an area just waiting to cause wound complications. One OB wrote in 2006:

In general, there is a lot to be said for an incision not buried under the pannus of fat, so that fresh air can help keep the wound dry.

As a result, many OBs were taught that when they did cesareans on high BMI women, vertical (up-down) incisions should be used instead of low transverse (side-to-side, either Pfannenstiel or Joel-Cohen) incisions in order to lower the risk for infection, separations, and other wound complications.

They meant well, but they were operating from flawed assumptions and outdated teaching. In other words, they hadn't actually studied whether or not vertical was better in high-BMI women, they just assumed it was, based on their biases about fat bodies. As the authors of Alanis 2010 state:

Our results...contradict classic teaching by veteran surgeons and obstetrical texts. It has been written that transverse abdominal incisions made under the pannicular fold exist in “a warm, moist, anaerobic environment associated with impaired bacteriostasis . . .[that] promotes the proliferation of numerous microorganisms, producing a veritable bacteriologic cesspool.” However, we are unable to locate any evidence to support this popular conclusion....

A "veritable bacteriologic cesspool"? What a terrible and disrespectful way for those obstetric texts to describe it. While deep skin folds can sometimes predispose to skin yeast and infections, it doesn't always and surgical incisions should not be based on conditions assumed to exist. Rather, care providers should be aware of the possibility and make decisions based on actual evidence of problems rather than an assumption of pathology.

Vertical Incisions Do Not Improve Outcomes

As noted, cesarean incision choice for very heavy women was usually based on traditional teachings and biased assumptions. When someone actually took the time to research these hypotheses, however, it was found that vertical incisions were no better, and in some studies were actually far more risky.
Let's do a quick review of the medical literature on this topic.

Vertical is More Risky

The Alanis 2010 study discussed above studied women with a BMI over 50. They found better outcomes with transverse incisions:

Vertical abdominal incisions were associated with increased operative time, blood loss, and vertical hysterotomy...Our results also support the use of Pfannenstiel incisions in obese patients with a large panniculus.

D'heureux-Jones 2001 also found that vertical incisions were associated with greater blood loss and poorer outcomes. They recommended a Pfannenstiel incision too.

In some studies the findings were more dramatic. In Wall 2003, vertical incisions presented 12x the risk for wound complications compared to transverse incisions. TWELVE TIMES the risk. That's a tremendous difference.

Thornburg 2012 found that the majority of wound complications (WC) were found in the vertical incision group (45.7% rate in vertical incisions, vs. 11.6% in transverse incisions). That's a very significant difference. They concluded:

In morbidly obese women both infectious and separation type WC are more common in vertical than low transverse incisions; therefore transverse should be preferred.

Vertical is No Improvement

Critics would point out that a number of studies did not find a statistically significant difference between vertical vs. low transverse incisions (Sutton 2016, Vermillion 2000, McLean 2012, Houston and Raynor 2000, Brocato 2013, and Bell 2011). Many researchers cite these studies to argue that there is no difference between incisions and the choice should be completely left to the surgeon's preference.

However, if they read the full text of these studies, the data usually showed a very clear trend towards more complications with vertical incisions. For example, 5 of the 6 above-cited studies found nearly double or more the rate of problems in the vertical incision group, yet the difference did not rise to statistical significance:

Bell 2011 found wound complications in 14.6% of the vertical incision group vs. 7.6% in the low transverse group

Vermillion 2000 found a 23% wound infection rate in the vertical group vs. a 6% rate in the low transverse group

McLean 2012 found a 20% rate of wound separation in the vertical group vs. a 10% rate in the low transverse group

Sutton 2016 found a 26.3% rate of wound complications in the vertical group vs. 14.8% in the low transverse group

Brocato 2013 found 2.7x the risk for wound complications in the vertical group

The problem here is that the number of patients in the vertical incision groups in these studies was extremely small and that is what is confusing the outcome. Bell 2011 had only 41 patients with vertical incisions; Brocato 2013 had only 45; Sutton 2016 had only 57; McLean 2012 had only 25; and Houston and Raynor 2000 had only 15 patients in their vertical comparison groups. Basically, the studies showing no significant difference had too few vertical incisions to be rigorously compared.The fact that the differences didn't rise to statistical significance doesn't mean that vertical incisions were just as safe; it just means that these studies were simply underpowered to show statistical significance between the groups. Summary

Larger studies do need to be done, but the majority of the evidence we have so far suggests that vertical incisions perform no better and often perform worse in obese women. Low transverse incisions are usually associated with better outcomes.
Bottom line, vertical incisions are associated with increased rates of wound complications, blood loss, and infections in obese women, even very obese women, as we have written about extensively before. In addition, vertical incisions are far more scarring and challenging to a woman's self-esteem and should ideally be avoided on that basis alone. It's also worth noting that although the best incision for each woman's unique anatomy and situation must be judged on an individual basis, low transverse incisions have been used successfully even in women of 400-500 pounds without poor outcomes.

Vertical Skin = Vertical Uterine Incisions

Image from swcare.net

Another problem is that several of these studies (Bell 2011, Alanis 2010, Sutton 2016) have also shown that when vertical skin incisions are done, they result in a higher rate of vertical uterine incisions (hysterotomies). Bell 2011 found that nearly 2/3 of all vertical skin incisions in obese women resulted in a vertical uterine incision as well.

Vertical abdominal incisions were associated with vertical hysterotomy in our study, usually a result of inadequate access to the lower uterine segment. When the incision extends into the contractile portion of the uterus, a vertical hysterotomy has a profound impact on future pregnancy. Therefore, it is important to incorporate practices, like transverse abdominal incisions, that facilitate low uterine incisions.

Low transverse skin incisions and transverse uterine incisions are definitely superior and must be the first option.

In recent years, more and more OBs began to use low transverse incisions in women of size. In fact, today the vast majority of high BMI women ─ even very high BMI women ─ who have cesareans have low transverse incisions. This is encouraging progress.

Still, many OBs cling to their teaching and use a vertical incision at a higher rate for obese women, especially "morbidly obese" and "super obese" women.

A 2016 survey of OBs revealed that while 84% preferred a transverse incision for obese women, 16% still preferred other incisions (usually vertical).

McLean 2012 found that 11% of high-BMI women were still being subjected to the riskier vertical incisions; Marrs 2014 (a very large, multi-region, multi-center study; see below) found that vertical incisions were used in a whopping 19% of high BMI women.

Between these documents, that's a vertical incision in about 1 out of every 5-10 cesareans done in obese women. So while progress has been made, vertical incisions are still distressingly common, and they are still putting the well-being of women of size at risk.

But What About That 2014 Study?

Some doctors have pointed to the Marrs 2014 study to justify continuing with vertical incisions. This was the one study that seemed to disprove the idea that transverse was better. (See the first abstract below, full text can be found here.)

This was a secondary analysis of the MFMU registry, which examined data from cesareans in 19 different regional hospitals. This analysis looked at incision complications after cesarean in women with a BMI of 40 or more. Since it was the largest study of its kind in obese women (597 vertical incisions, 2603 transverse incisions), its conclusions were assumed to be far more powerful and definitive.

In the study, wound complications were found in 1.7% of women with transverse incisions vs. 4.2% of women with vertical incisions. In other words, more than double the rate of problems were found with vertical incisions. Simple conclusion to be drawn, right? Not quite.

In its univariate (one variable) analysis, transverse was shown to be the safer incision. But in its multivariate (multiple variable) analysis, the opposite was found ─ vertical seemed better. This conclusion was trumpeted far and wide because now there was research ammo to keep justifying the use of vertical incisions in high-BMI women.

However, a re-analysis of the data shows that their conclusion was wrong and transverse was better after all. Turns out they used the wrong figures in their multivariate analysis and so got the wrong conclusion. Instead of vertical being the better incision, it was actually transverse that had the best outcomes. The authors issued a retraction in July of 2017 and stated:

The original publication reported that univariate analysis showed that a vertical skin incision in obese women undergoing Cesarean delivery was associated with a higher odds ratio for wound complications than a transverse skin incision. Multivariable analyses showed a reversal of the association (i.e. the odds of wound complications were lower in women with a vertical skin incision). However, there was an error in the way the variable was entered in the logistic analysis. Re-analysis with the correct coding of the variable indicates that a transverse skin incision is associated with decreased odds of wound complication compared to a vertical skin incision.

Well, bravo that they finally published a retraction to the previous study and a corrected abstract...3 years after the fact. (I have published the abstracts to both below for comparison.)

At least they actually printed a retraction and admitted their error. Usually these are just glossed over. But I'm irritated because the damage has been done. How many OBs have gotten the wrong impression and won't see the retraction? How many young doctors have been erroneously taught that vertical incisions were superior for high BMI women?

How many high-BMI women have had the more dangerous vertical incision in the meantime and how many will continue being subjected to it because of the error in that original study? How many medical schools and textbooks will continue teaching that vertical incisions are better?

Grrrrrrrr. Mistakes happen, but this is a mistake with long-lasting implications for larger women. I can't believe they were sloppy enough to make this mistake in the first place and then not discover it for three years. I also question whether they are doing enough to reach out to correct the mistaken teaching and care practices that are in place because of this egregious error. If it's not addressed aggressively, incorrect teachings and practices will remain in place, and that could have a lot of negative health implications for women of size.

Conclusion

Low transverse cesarean scar in a high BMI woman;these are usually minimally noticeable after a few years

A vertical skin incision on a high BMI woman has far more noticeablescarring and potential impact on her self-esteem

Proper choice of cesarean incision is one key way to reduce complications in obese women. Thankfully, most OBs recognize that a low transverse is the best incision in high BMI women, and use it most of the time.

However, some OBs continue to insist that vertical is better, especially as BMI increases. One 2014 study found only a 2% rate of vertical incisions in women with BMIs between 30 and 40, but this increased to more than 15% in women with a BMI over 50. The fact that the Marrs MFMU study found that vertical incisions were used in 19% (nearly 1 in 5 cesareans of obese women) in women with a BMI over 40 is quite alarming. These high rates are risking the health and well-being of women of size.

Furthermore, OBs have even been known to use a vertical incision to discourage their "morbidly obese" patients from having more children. This is appalling example of weight stigma. Here is one woman's story:

When she came in to discuss my surgery, the OB sat down and asked me if I wanted my tubes tied while she was in there. I was shocked and told her no, that this was my first child, and I didn't want to make decisions like that at the moment. And she countered with a speech that boiled down to 'You are too fat to have any more children, you shouldn't even be having this one, and if I had anything to do with it, you wouldn't be.'...[Afterwards] the hateful OB informed me that the kind of incision that they made in my uterus will make it incredibly dangerous for me to attempt another pregnancy...a subsequent pregnancy could cause the uterus to rupture and I would die horribly from a hemorrhage.

Granted, there are sometimes circumstances which compel the use of a vertical incision. An extremely large belly makes it harder to locate anatomical landmarks; sometimes the panniculus is so large it is impossible to place an incision beneath it; sometimes there is an active skin infection present in the folds; sometimes other factors like fetal or placental position make a different incision safer. In those situations, there are other incision options, including a vertical or a higher transverse (Joel-Cohen) incision. However, this mother had none of these considerations. The incision seems to have been chosen purely to punish the mother and to strongly discourage further children despite her refusal of sterilization.

Whatever the reasons, there is no justification for such a high rate of vertical incisions still being used in heavy women. Medical schools and educational materials need to stop teaching that a vertical incision is the incision of choice for high BMI women.Research CLEARLY shows that a vertical incision performs no better than a transverse one in obese women and in most research, is actually associated with worse outcomes. NO study now shows a better outcome with vertical incisions.

The bottom line is that incision choice for each woman of size must be evaluated on its individual circumstances, but a low transverse incision should be the default choice in nearly all high BMI women. As one OB said in a conference presentation to colleagues:

The bottom line is that vertical incisions should not be used in obese patients...Vertical incisions are being used less and less in these patients, but just don't do it.

This article has been removed: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been removed at the request of the Editors-in-Chief and Authors. The original publication reported that univariate analysis showed that a vertical skin incision in obese women undergoing Cesarean delivery was associated with a higher odds ratio for wound complications than a transverse skin incision. Multivariable analyses showed a reversal of the association (i.e. the odds of wound complications were lower in women with a vertical skin incision). However, there was an error in the way the variable was entered in the logistic analysis. Re-analysis with the correct coding of the variable indicates that a transverse skin incision is associated with decreased odds of wound complication compared to a vertical skin incision.

Studies Which Show Poorer Outcome with Vertical Incisions in Obese Women

Saturday, August 12, 2017

Many women with a prior cesarean who want a Vaginal Birth After Cesarean (VBAC) are counseled that they are not "good candidates" for a trial of labor because a VBAC Prediction Model suggests that they have a very low chance of VBAC "success."

In particular, the MFMU VBAC Prediction Model considers weight a strong negative predictive factor for VBAC. As a result, many obese women are told that their chances for VBAC are very low, implying they might as well just sign up for the repeat cesarean now. Many doctors strongly discourage VBAC in women with a high Body Mass Index (BMI). Some hospitals and practices even have BMI restrictions on who is allowed to have a Trial of Labor After Cesarean (TOLAC).

Similarly, many women of color are discouraged from pursuing a VBAC because they are told that they have a lower chance of success. Imagine the negative pressure against VBAC when these two factors intersect in a high BMI woman of color!

However, a recent study from UCLA actually examined how predictive this model was in their institution. They found that it was highly accurate for women predicted to have a very strong chance of VBAC. But to their surprise, they found it was NOT that accurate for women predicted to have a low or moderate chance of VBAC.

The difference was particularly striking for those predicted to have a low chance of a VBAC. 57% of this group actually had a VBAC, when only 29% were predicted to have one, nearly twice the expected rate. Of particular note, the authors also documented that, unlike the MFMU prediction model, neither BMI nor ethnicity were associated with lower rates of VBACs in their institution.

This is especially meaningful to the many women of color and women of size who have been actively discouraged from pursuing a VBAC because of the MFMU prediction model. It also suggests to me that risk perception and the way women are managed in labor (higher induction rates and a lower surgical threshold are common in TOLAC in high BMI women, for example) may influence VBAC "success."

Personally, my VBAC prediction scores were extremely low (22%!) due to multiple risk factors, yet I went on to have not one but two VBACs. If I had let negative predictions discourage me, I would have missed out on my VBACs and their easier recoveries, and I would have been exposed to increased risk for placenta previa and accreta by having additional scars on my uterus.

I know from my work with the International Cesarean Awareness Network (ICAN) that many women are told they have a poor chance at a VBAC and yet go on to have a VBAC anyhow. In fact, few women meet all the "ideal conditions" for VBAC success, yet most will go on to have a VBAC.

If you have been told that you are not a good candidate for VBAC because of your BMI, your race, or various other factors, remember this study and the anecdotal experience of so many women in ICAN. It's okay to consider risk factors, but don't let them overly influence your decision. Group risk factors don't predict what will happen with any one individual.

No one can guarantee you a VBAC, but neither can anyone reliably predict who will not have a VBAC when given a fair and adequate chance to labor. As the authors conclude in the UCLA study:

As part of efforts to safely decrease cesarean rates in the United States, patients interested in TOLAC (and their providers) should not be discouraged by a low predicted success score.

OBJECTIVE: To investigate the validity of a prediction model for success of vaginal birth after cesarean delivery (VBAC) in an ethnically diverse population. METHODS: We performed a retrospective cohort study of women admitted at a single academic institution for a trial of labor after cesarean from May 2007 to January 2015. Individual predicted success rates were calculated using the Maternal-Fetal Medicine Units Network prediction model. Participants were stratified into three probability-of-success groups: low (<35%), moderate (35-65%), and high (>65%). The actual versus predicted success rates were compared. RESULTS: In total, 568 women met inclusion criteria. Successful VBAC occurred in 402 (71%), compared with a predicted success rate of 66% (p = 0.016). Actual VBAC success rates were higher than predicted by the model in the low (57 vs. 29%; p < 0.001) and moderate (61 vs. 52%; p = 0.003) groups. In the high probability group, the observed and predicted VBAC rates were the same (79%). CONCLUSION: When the predicted success rate was above 65%, the model was highly accurate. In contrast, for women with predicted success rates <35%, actual VBAC rates were nearly twofold higher in our population, suggesting that they should not be discouraged by a low prediction score.

Because people of all sizes deserve compassionate, gentle, helpful care.

The Well-Rounded Mama Blog

Painting by Mary Cassat, 1844-1926. Image from Wikimedia Commons.

Blog Mission

I write about health for people of size, plus-size pregnancy and birth, pregnancy and childbirth in general, parenting, and Health At Every Size®.

It is time for frank discussion about how fat people are treated in healthcare and how care for this group can be improved. It is also time for some common-sense information, without scare tactics or judgment, about pregnancy in women of size.

About The Author

I am a childbirth educator, writer, and mother to four kids. I also write at www.plus-size-pregnancy.org, and can be emailed at kmom at plus-size-pregnancy dot org.

Disclaimer

This site is written by healthcare consumers for healthcare consumers. The information provided here is not intended as medical advice. Consult your personal healthcare providers when deciding how to use this information.